Re: [DNSOP] [dnsext] Re: Computerworld apparently has changed DNS protocol

[George Michaelson <[e-mail]>]

On 11/11/2009, at 3:29 PM, Duane Wessels wrote:

> 
> 
> On Wed, 4 Nov 2009, Nicholas Weaver wrote:
> 
>> Also, has someone done a study what the major recursive resolvers do on response failures from a root?  Do they go to another first or do they try a smaller EDNS MTU?
> 
> I gave a presentation on this at the DNS-OARC meeting last week:
> 
> https://www.dns-oarc.net/files/workshop-200911/Duane_Wessels.pdf
> 
> I was only able to test BIND (9.4.3) and Unbound (1.3.3) before the
> workshop.
> 
> I've since learned that since my graphs only show 7 seconds after
> the initial query, it misses Unbound's fallback to TCP, which
> takes longer than that.

Great presentation.

I encourage everyone to read this document. Duane shows an incredibly high packet amplification in some circumstances, of 30 or more subsequent (sys/glue) queries each having to hunt to the optimal MTU.

And the total traffic count rises as well of course.

yes, its a corner case. Alas, its a corner case we can predict will exist for disadvantaged people behind broken middleware and old software.

-George